Document Type : Original Article
Authors
1 aculty of Desert Studies, Semnan University,
2 Faculty of Desert Studies, Semnan University
Abstract
Drought is a major natural hazard with widespread impacts on agriculture, water resources, and food security. This study aimed to assess the spatiotemporal characteristics of seasonal agricultural drought across the counties of Hamadan Province and to model it using teleconnection patterns. The Temperature-Vegetation Dryness Index (TVDI) was extracted seasonally from Google Earth Engine using MODIS Terra satellite imagery (2003–2022), and its spatiotemporal dynamics were analyzed. TVDI trends were assessed using the Mann-Kendall and Sen's slope tests. Additionally, the correlation between 13 teleconnection patterns and TVDI was evaluated; indices with the strongest correlations were selected for multiple linear regression (MLR) modeling. The highest seasonal mean TVDI occurred in summer (0.90 in Razan and Famen), while the lowest occurred in winter (0.38 in Asadabad). On an annual scale, Famenin recorded the highest mean TVDI (0.87) and Malayer the lowest (0.49). TVDI showed a significant increasing trend on both seasonal (excluding autumn) and annual scales, with slopes ranging from 0.005 to 0.001 and 0.003 to 0.002, respectively. Drought zoning indicated that most of the province falls under moderate to severe drought classes. TVDI correlated significantly with GLOBALST, NAO, and PDO at certain time lags, and with AMO across all lags from 0 to 12 seasons. The AMO-based MLR model demonstrated strong performance in estimating TVDI, with an RMSE of 0.093, R² of 0.78, and Nash-Sutcliffe efficiency of 0.76.
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